This invention relates to devices for handling cores upon which webs of paper or other materials are to be wound and, more particularly, to an improved coreholder for facilitating the rapid securement, winding or unwinding of a core by rotation thereof, and for removal thereafter.
There have been proposed many different bushings, reel holders or grabbers, or so called coreholders. In one such prior art type of coreholder, a cam or eccentric may be rotated for selectively engaging the inner diameter of a core to be received. Such cores, as used to hold webs of paper, fabric or other material such as will be fed into a printing process, as in the manufacture of printed labels, are of material which can be caused to distort as the eccentric or coreholding mechanism is expanded or extended into its core-engaging position. The resultant distortion and eccentricity of the tape roll causes the tape roll to surge or undergo positive and negative acceleration during each rotation of the coreholder, and this can in turn result in registry problems during printing. Another problem of such prior arrangements is that the core-engaging mechanism sometimes becomes loosened. The resultant inertia of the rotating roll will cause it to spin relative to the coreholder, and this can cause tape to become unrolled and to spill from the core, since the drive mechanism can no longer exert a braking force on the roll.
Among the prior art may be noted the following references: Damon U.S. Pat. No. 1,527,539; Taylor U.S. Pat. No. 1,858,753; and Reynolds U.S. Pat. No. 2,507,577.
The Damon patent discloses a spindle which includes a plurality of bars urged outwardly from a spindle assembly, the bars being selectively moveable radially in or out for selective engagement of the interior surfaces of a core or reel. However, the surface area of such bars is limited and thus there is potential for slippage or lack of secure engagement of the core or reel. Further, the bars in such an arrangement undergo longitudinal translation in movement between the retracted and extended, core-engaging positions, and such movement is disadvantageous. The Taylor patent reveals an expansible bushing for winding cores having a wedge-shaped key intended to be forced progressively between two halves of the bushing to expand the bushing outwardly for engaging the inner surfaces of the core. It is found, however, that such a wedge produces an inherent distortion of the bushing which, as a result, does not exhibit a uniform diameter or concentricity relative to the axis of rotation. Accordingly, the core is similarly distorted upon expansion of the bushing, with all of the foregoing disadvantages.
The Reynolds patent proposes an expanding arbor type reel grab having a series of rollers on opposite sides of a wedge-shaped tapered arbor which, by means of a lever-actuated mechanism, may be caused to be displaced along the surface of the tapered surfaces of the tapered arbor for outwardly expanding two halves of the core. In addition to being prohibitively complex, this construction is of relatively massive configuration and has a cumbersome and complicated tightening mechanism having dangerous extending elements which constitute a hazard to personnel when the core is rotating.
Accordingly, it is among the several objects of the present invention may be noted the provision of an improved coreholder which is of simple and highly effective construction; which provides uniform expansion of core-engaging elements; which is inherently self-equalizing; which utilizes conventionally-available, highly precise elements in its construction; which securely and reliably engages a core to prevent the same from rotating relative to the coreholder; which permits simple, facile tightening for rapid mounting of a core, and equally simply, facile removal of the core; and which does not provide objectionable eccentricity or rotational acceleration of the core, when engaged upon the coreholder, during rotation.
Briefly, the new coreholder of the invention, as used for securely holding web cores and the like for winding and unwinding thereof, comprises a body of generally cylindrical configuration. An expandable sleeve surrounds the body for receiving a core with the sleeve extending within the central opening of the core. The body defines grooves along its surface beneath the sleeve, and a plurality of balls, as most preferably in the form of ball bearings, of uniform diameter, extend along the lengths of the grooves in contiguous relationship such that some of the balls will be forced radially outwardly toward the sleeve for applying pressure thereto upon pressure exerted relatively between the balls. At least one of the grooves opens from the body at one end thereof for exposing an end one of the balls. Means is provided for selectively applying pressure against the exposed ball to transfer pressure to others of the balls for causing the balls to apply pressure to the sleeve for producing outward expansion thereof for uniformly and grippingly engaging interior surfaces of the core central opening.
Other objects and features will be in part apparent and in part pointed out hereinbelow.